A photovoltaic power generation system includes a solar cell string as a DC power source. The solar cell string includes a plurality of solar cell modules connected in series. Defects may arise in a solar cell string, such as malfunctions in solar cell modules or breakage in cables connecting solar cell modules to each other. When such a defect arises in a solar cell string, it is necessary to repair the defective location. Inspection apparatuses or inspection methods for inspecting whether or not there is a defect in a solar cell module or a solar cell string have been disclosed in the past.
JP 2012-238716A (published Dec. 6, 2012), JP 2016-93039A (published May 23, 2016), JP 2008-91828A (published Apr. 17, 2008), and JP 2009-21341A (published Jan. 29, 2009) are examples of the related art.
However, the solar cell panel abnormality detection apparatus disclosed in JP 2012-238716A is configured to determine whether or not there is a defect in one of a plurality of solar cell panels constituting a solar cell string, and whether or not there is a defect in a bypass diode connected between positive and negative terminals of the solar cell panel. The abnormality detection apparatus must therefore inspect each of the plurality of solar cell panels and each of the plurality of bypass diodes individually, and thus cannot easily determine whether or not there are defects in a plurality of locations in a solar cell string.
JP 2016-93039A describes an inspection method and an inspection apparatus that inspect a plurality of locations in a solar cell string for defects, where a cutout relay that cuts conduction partway along the solar cell string is used. In other words, the solar cell string is split into two strings by the cutout relay, and inspection values indicating whether or not there is a malfunction in a single location are obtained for each of the two strings. Thus like JP 2012-238716A, the inspection method and inspection apparatus according to JP 2016-93039A cannot easily determine whether or not there are defects in a plurality of locations in a solar cell string.
The solar cell array defect diagnostic methods disclosed in JP 2008-91828A and JP 2009-21341A, meanwhile, disclose techniques for inspecting whether or not there is a defect in a single location of a solar cell string, but neither disclose nor suggest determining whether or not there are defects in a plurality of locations.
Having been achieved in light of the above-described circumstances, one or more aspects may provide an inspection technique capable of easily determining whether or not there are defects in a plurality of locations of a solar cell string.